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    <title>Document</title>
</head>
<body>
    <ul>
        <li>1</li>
        <li>2</li>
        <li>3</li>
        <li>4</li>
        <li>5</li>
    </ul>

    <a href="https://www.bilibili.com/">bilibili</a>

    <form action="https://www.bilibili.com/">
        <input type="submit">
    </form>
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        var a = document.querySelector('a')
        var form = document.querySelector('form')

        ul.addEventListener('click',function(){
            console.log(100)
        })

        a.addEventListener('click',function(e){
            e.preventDefault()
            console.log('a')
        })
        form.addEventListener('submit',function (e) {
            e.preventDefault()
            console.log('form')
        })
    </script>
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